MediPlas achieved the reduction over 6-log levels for different bacteria

Over the last few weeks, the Versuchs- und Lehranstalt für Brauerei in Berlin (VLB) e.V. has carried out extensive tests with the MediPlas RONS generator to reduce live cell counts. The experiments showed that, depending on the type of bacteria, the MediPlas system achieved a reduction in live cell counts of more than 6 log levels after just 5 minutes or after a maximum treatment time of 15 minutes. Both gram-positive (Bacillus subtilis) and gram-negative (Escherichia coli) bacteria were utilised in the experimental setup.

In recent years, relyon plasma GmbH has developed the MediPlas system in accordance with high medical standards. It consists of an efficient generator for reactive oxygen and nitrogen species (RONS) and a perfectly matched high-voltage generator. By selecting the input parameters such as the type of process gas, flow rate, driver voltage and active temperature control, the chemical composition of the RONS can be deliberately influenced (ozone chemistry or nitrogen oxide acids). This is a great advantage in the context of disinfection and sterilisation, as it allows customer-specific optimised settings.

Experimental setup

A microorganism suspension is introduced into a reaction vessel filled with water at the start of the experiment. The RONS generated by the MediPlas system are introduced into the vessel via a sintering stone and flow through the contaminated water. After certain time intervals, samples are taken to analyse the colony-forming units (CFU).

The log level was then determined by taking a sample from the reaction vessel. Log levels (log 1 to log 8) are used to categorise the effectiveness of a disinfection in terms of killing pathogens. A 5 log reduction means a reduction of 99.999% of pathogens, a 6 log reduction of 99.9999%.

Results

The series of experiments shows that for gram-positive Bacillus subtilis bacteria, a reduction in live cell counts of 5 log levels was achieved after a treatment period of 5 minutes with RONS. With a treatment duration of 15 minutes, a reduction of more than 6 log levels was even achieved.

In the treatment of gram-negative bacteria Escherichia coli, a reduction of more than 6 log levels was achieved after just 5 minutes of treatment.

The investigation was limited to 6 log levels, so there are no further results for even higher log levels.

The series of tests at the VLB Berlin shows that the MediPlas system can be successfully used to sterilise both gram-positive (Bacillus subtilis) and gram-negative (Escherichia coli) bacteria.

The special feature of the MediPlas system is that all parameters such as gas flow, power, frequency, duty cycle and temperature can be set individually. This means that individual settings can be made for each microorganism in order to achieve the best possible reduction of live cell counts. The MediPlas system has been developed as a component system so that the MediPlas Reactor and MediPlas Driver can be integrated directly into the customer’s product. This allows the MediPlas system to be integrated as a disinfection unit or added to existing disinfection systems.

This opens up a wide range of possible applications for the MediPlas system in medicine and industry for disinfection.